Page 318 VOJNOSANITETSKI PREGLED Vojnosanit Pregl 2016; 73(4): 318–325.

UDC: 616.31::616.716.716.4-007-08 ORIGINAL ARTICLE DOI: 10.2298/VSP141210051M

Radiographic cephalometry analysis of condylar position after bimaxillary osteotomy in patients with mandibular Rendgen-kefalometrijska analiza pozicije kondila nakon bimaksilarne osteotomije mandibularnog prognatizma

Nikola D. Miković*, Miloš M. Lazarević*, Zoran Tati憇, Sanja Krejović- Trivić†, Milan Petrović*, Aleksandar Trivić§

*Clinic of Maxillofacial Surgery, Faculty of Dentistry, University of Belgrade, Belgrade, Serbia; †Clinic of Oral Surgery and Implantology, Military Medical Academy, Belgrade, Serbia; ‡Faculty of Medicine of the Military Medical Academy, University of Defence, Belgrade, Serbia; §Clinic of Otorhinolaryngology and Maxillofacial Surgery, Clinical Center of Serbia, Faculty of Medicine, University of Belgrade, Belgrade, Serbia

Abstract Apstrakt

Background/Aim. Postoperative condylar position is a Uvod/Cilj. Postoperativna pozicija kondila je značajna za substantial concern in surgical correction of mandibular hiruršku korekciju mandibularnog prognatizma. Ortognat- prognathism. Orthognathic surgery may change condylar ska hirurgija može da promeni poziciju kondila, a to može position and this is considered a contributing factor for ear- biti jedan od faktora koji doprinosi ranom skeletnom recidi- ly skeletal relapse and the induction of temporomandibular vu i pojavi temporomandibularnih disfunkcija. Zbog toga je disorders. The purpose of this study was to evaluate cilj ove studije bio da proceni promene pozicije kondila kao changes in condylar position, and to correlate angular skele- i da ne korelišu promene pozicije kondila sa angularnim ske- tal measurements following bimaxillary surgery. Methods. letnim promenama nakon bimaksilarne hirurgije. Metode. On profile teleradiographs of 21 patients with mandibular Na telerendgenskim snimcima 21 bolesnika sa mandibular- angular and linear parametres, the changes in condylar posi- nim prognatizmom mereni su angularni i linearni parametri tion, were measured during preoperative orthodontic treat- koji opisuju promene u položaju kondila, pre ortodontske ment and 6 months after the surgical treatment. Results. A pripreme i šest meseci nakon hirurške korekcije. Rezultati. statistically significant difference in values between the Ustanovljena je statistička značajnost razlika u vrednosti pa- groups was found. The most distal point on the head of rametara između grupa. Tačka DI – najdistalnija tačka na condyle point (DI) moved backward for 1.38 mm (p = glavi kondila, pomerila se unazad 1,38 mm (p = 0,02), a tač- 0.02), and the point of center of collum mandibulae point ka DC – tačka koja označava centar collum mandibulae, (DC) moved backward for 1.52 mm (p = 0.007). The pomerila se, takođe, unazad za 1,52 mm (p = 0,007). Vred- amount of upward movement of the point DI was 1.62 mm nost pomeranja tačke DI naviše bila je 1,62 mm (p = 0,04). (p = 0.04). Conclusion. In the patients with mandibular Zaključak. Kod bolesnika sa mandibularnim prognatiz- prognathism, the condyles tend to migrate upward and for- mom, kondili su težili da migriraju unapred i naviše šest me- ward six months after bimaxillary surgery. seci nakon bimaksilarne operacije.

Ključne reči: Key words: prognatizam; hirurgija, maksilofacijalna; prognathism; surgery, oral; postoperative period; postoperativni period; kefalometrija; cephalometry; temporomandibular joint; centric relation. temporomandibularni zglob; centrički odnos.

Introduction MP is complex and includes preoperative orthodontic treatment and orthognatic surgery. In some severe cases both mandibular Mandibular prognathism (MP) or skeletal Class III maloc- and maxillary osteotomy are needed. One of the preferred surgi- clusion with a prognathic has long been viewed as one cal procedures for the correction of mandibular prognathism, of the most severe maxillofacial deformities 1. The treatment of since its introduction by Trauner and Obwegeser 2, is billateral

Correspondence to: Nikola D. Miković, Clinic of Maxillofacial Surgery, Faculty of Dentistry, 11 000 Belgrade, Serbia. E-mail: [email protected] Vol. 73, No. 4 VOJNOSANITETSKI PREGLED Page 319 sagittal split osteotomy (BSSO). Another popular technique, The presurgical protocol included preoperative ortho- mostly used for maxillary reposition, is Le Fort I osteotomy. In dontic treatment, model surgery, cephalometric and photo- some severe cases of MP both mandibular and maxillary . The preoperative orthodontic trea- osteotomy are needed, and that form of correction is commonly tment lasted from 18 to 24 months. known as bimaxillary surgery. The surgery began with soft tissue incision and initial One of the goals of bimaxillary surgery is maintaining osteotomy of the ramus of the mandible as in BSSO, but skeletal and occlusal stability. Occlusal stability, which is with no definitive separation of bone fragments. The one of the most important factors in the prevention of pos- wound was filled with gauze soaked in saline and then the toperative relapse in orthognathic surgery, results from go- complete Le Fort I osteotomy was done. Using the interoc- od dental occlusion and a normal postoperative condylar clusal splint and maxillo-mandibular fixation, the maxilla position 3. Condylar processus is a part of the mandibular was positioned in a certain position and fixed with mono- ramus and a part of the temporomandibular joint (TMJ), cortical screws (at least four) and L-shaped plates. After specific to the human body in its morphology, position and fixing the maxilla, the maxillo-mandibular fixation was re- function 4. This makes it particularly important, both in moved, so the separation of mandibular bone fragments functional and in anatomical terms, because of its shape was completed. A separated central fragment of mandible and position depending on the position of the mandible, the was placed in the correct occlusion with the maxilla, the function of the TMJ and facial appearance 5. Good dental intermaxillary fixation was restored, and bone fragments of occlusion depends on normal temporomandibular joint; that the mandible were fixed with monocortical screws and pla- is, dental or abnormal interdigitation with tes. Monocortical screws were located on the buccal surfa- normal condylar position can be controlled postoperatively ce of the mandible, three of them on each side of the by orthodontic treatment, but an abnormal condylar positi- osteotomy line. Rigid intermaxillary fixation was maintai- on can not be corrected postoperatively and eventually dis- ned for 6 to 8 weeks and after that period of time, the elas- rupts postoperative occlusal stability 3. Therefore, postope- tic fixation was maintained for 4 weeks. Postoperative ort- rative condylar position is a substantial concern in the sur- hodontic treatment started 6 to 8 weeks after the surgery. gical correction of a mandibular prognathism. Orthognathic Standardized lateral cephalometric radiographs were surgery may change condylar position and this is conside- obtained at the following 2 stages in all the patients: before red a contributing factor for early skeletal relapse 6–9 and the preoperative orthodontic treatment (T1) and 6 months the induction of temporomandibular disorders (TMDs) 10–13. after the surgical treatment (T2). Positional changes in the condyle have been hard to The machine used to obtain lateral cephalometric ra- recognize and accurately measure following orthognathic diographs was Ortoceph (Simens, Germany). The scanning surgery 14, 15. Displacement of the condyle can be expected settings of the machine were: 65–80 kVp tube voltage, 20 as a result of four variables: anterior-posterior, vertical, mA tube current, and 1–1.5 second scan time. All the pati- medial-lateral, and along the long axis of the condyle 16. ents sat in an upright position with the teeth in centric oc- The purpose of this study was to evaluate changes in clusion. The patients’ Frankfort horizontal (FH) plane was condylar position, and to correlate angular skeletal measu- parallel to the floor. rements following bimaxillary surgery in patients with Cephalometric radiographs were scanned by a scanner mandibular prognathism. EPSON 1600 PRO (Japan) into jpg format. In that way all the radiographs were converted into digital form. The Methods software Ax Ceph version 2.3 (Audax, Slovenia) was used for computerized cephalometric analysis. Cephalometric The study included 21 patients (13 males, 8 females; analysis was carried out by one examiner and included the ages between 18–25 years). Clinical examinations and sta- reference points and lines shown in Figures 1 and 2. ndardized lateral cephalometric radiographs were conduc- Analyses were performed twice by the same examiner, on ted at the Belgrade University Faculty of Dentistry. The different days. Statistically significant differences did not study was approved by the Ethics Committee at the Faculty appear between these two analyses. of Dentistry in Belgrade. Informed consent was obtained Certain linear and angular parameters were used to de- from each patient. All the patients were diagnosed with fine the position of the condyle pre- and postoperatively mandibular prognathism on the basis of the following crite- (Table 1). Angular parametres included: SNA – the angle ria: the angle of mandibular prognathism (SNB) ≥ 80°; the of maxillary prognathism; SNB – the angle of mandibular angle of sagittal intermaxillary relationship (ANB) ≤ 0°; prognathism; ANB – the angle of sagittal intermaxillary re- reverse overlap of the frontal teeth and relationship of the lationships; Cd-DC-Xi/FH – the angle formed by centerline first permanent molars in Class III, and had ended the of mandibular rami and X axis; ArGoMe – gonial angle growth and development of orofacial system. The patients (angle of the mandible); Sna-Snp/FH – the angle formed by with mandibular prognathism as a result of severe facial the main plane of maxilla and X axis. Linear parametres asymmetry, deformity secondary to trauma, syndromes, pa- were the distances between the points Go, Ar, DC, Cd, PI, tients with systemic disease, degenerative joint disease, and CI, A, B and Y axis; and distances between the points Go, with signs and symptoms of temporomandibular Ar, DC, Cd, PI, CI, A, B and X axis (see Abbreviations in dysfunction were not included in the study. addendum).

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Fig. 1 – Reference points included in the analysis. S (sella) – The point representing the geometric center of the sella turcica.; N (nasion) – The most anterior (midline) point of the frontonasal suture; A (subspinale) – The deepest point in the bony concavity in the midline below the anterior nasal spine; Or (orbitalis)- The point representing the lowest point on the inferior orbital rim; Po (porion) – The most superior point of the external auditory meatus; Sna (spina nasalis anterior) – The most prominent point of maxilla; Snp (spina nasalis posterior) – The most distal point of the conjunction of palatinal bone and pterygomaxillar fissure; B (supramentalis) – The innermost point on the contour of the mandible between the incisor tooth and the bony chin; Me (menton) – The lowest point of the mandibular symphysis; Go (gonion) – the midpoint of the mandibular angle between the ramus and mandibular body; Cd (condylion) – the most posterosuperior point on head of the condyle; Ar (articularis) – The point midway between the two posterior borders of the left and the right mandibular rami at the intersection with the basilar portion of the occipital bone; DI – The most distal point on the head of the condyle; PI – The most anterior point on the head of the condyle; DC – The center point of the collum mandibulae on the Ba-N line; Xi – The point located at the geographic center of the ramus; Ba (basion) – The point of the anterior margin of the foramen magnum – The midpoint of the curvature between upper and the lower surfaces of the basilar portion of the occipital bone.

Fig. 2 – Reference planes included in the analysis. N-S – The main plane of the anterior cranial base; Go-Me – The main plane of the mandible body; Sna-Snp – The main plane of the maxilla; Cd-DC-Xi – the centerline of the mandibular rami; X axis (Or-Po Frankfort horizontal (FH)) – The horizontal plane of the head; Y axis – The vertical plane which is normal to the X osis and goes from the point S.

Table 1 Linear and angular parameters included in the analysis Linear parameters (millimeters) Angular parameters (degrees) Go-Y axis Cd-DC-Xi / FH Ar- Y axis ArGoMe DC- Y axis Sna-Snp / FH Cd- Y axis ANB PI- Y axis SNB CI- Y axis SNA A- Y axis B- Y axis Go- X axis Ar- X axis DC- X axis Cd- X axis PI- X axis CI- X axis A- X axis B- X axis SNB – Angle of mandibular prognatism; ANB – Angle of sagittal intermaxillary relationship; SNA – sella nasion, A point. See abbreviations in Addendum.

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Using the software, after insertion the digital (jpg) format of used to describe rotation of the maxilla after bimaxilary lateral cephalogram, calibration was set up. The calibration is surgery (see Abbreviations in addendum). used to convert pixels of the inmages into milimetres. A me- Data analysis was not preformed until the last patient tal ruler on a cephalostat which is visible on was had been examined for the last time to prevent bias from the used for calibration (Figure 3). examiner’s awareness of any trends in the basic data. Statistical analyses were performed with SPSS version 15 (SPSS, Chicago, Ill). For the assessment of the differences between angular and linear parameters before (T1) and after (T2) the surgery, Students paired t-test was used. Pearsons cor- relation was used to correlate changes in condilar position with angular skeletal changes following bimaxillary surgery. The differences were considered significant at p < 0,05.

Results

Horizontal skeletal changes: the mean setback of the man- dible 6 months postoperatively (T2-T1) was 0.91 mm at point B but the differences were not statistically significant (p = 0.658). Point Go showed tendency to go forward (1,19 mm) but also was not statistically significant (p = 0.242). On the other hand, maxilla was on average moved forward 3.29 mm at point A (p = Fig. 3 – Calibration of the digital image usig the software 0.0038) (Table 2). Horizontal changes in condylar position: six “Ax Ceph”. months after the surgery the position of point DI and DC chan- Then, the location of reference points and lines were de- ged significantly. Point DI moved backward 1.38 mm (p = fined. To analyze linear (anterior-posterior and vertical) mo- 0.02), likewise, point DC moved backward for 1.52 mm (p = vement of the condyle, in every cephalometric radiograph the 0.007). The movement of the points PI and Cd were not coordinate system with X and Y axis (as described in Figure 2) statistically significant, but it was noted that point PI showed the was inserted. After that, the distance between the points Go, tendency to move forward by 0.1 mm (Table 2). Ar, DC, Cd, PI, CI, A, B and Y axis was measured to determi- Vertical skeletal changes: the results showed the tendency ne horizontal skeletal changes postoperatively. The distance of downward movement of the mandible at points B and Go between the points Go, Ar, DC, Cd, PI, CI, A, B and X axis (1.43 mm, p = 0.644; 3.85 mm p = 0,058, respectively). Maxilla was measured to determine vertical skeletal changes was moved upward at point A for 3.18 mm but showed no stati- postoperatively. Angles SNA, SNB, and ANB were used to stical significance (Table 3). describe skeletal changes after the intervention. The angle Ar- Vertical changes in condylar position: the position of Go-Me and angle Cd-DC-Xi/FH were used to analyze rotation condyle changed only at point DI. The amount of upward mo- of the condyle after the intervention. Angle Sna-Snp/FH was vement of point DI was 1.62 mm (p = 0.04). Points PI and DC

Table 2

Distances between the reference points and Y axis Distances (mm) n ґ SD Med Min Max p T1 21 60.48 14. 84 65.00 39.00 100.00 YB 0.658 T2 21 59.57 10.82 60.00 37.00 85.00 YA T1 21 59.52 11.26 60.00 45.00 82.00 0.0038* T2 21 62.81 8.01 63.00 47.00 79.00 YDI T1 21 17.38 3.69 16.00 12.00 26.00 0.020* T2 21 18.76 4.21 19.00 8.00 24.00 YPI T1 21 6.48 3.31 6.00 1.00 13.00 0.653 T2 21 6.38 3.15 6.00 0.00 11.00 YCd T1 21 14.38 3.97 14.00 8.00 24.00 0.446 T2 21 14.86 3.62 16.00 6.00 20.00 YDC T1 21 9.19 3.70 10.00 2.00 16.00 0.007* T2 21 10.71 3.94 11.00 2.00 17.00 YAr T1 21 15.33 4.08 15.00 8.00 23.00 0.005* T2 21 16.86 3.92 16.00 7.00 23.00 YGo T1 21 7.00 6.32 6.00 0.00 24.00 0.242 T2 21 8.19 5.95 6.00 0.00 20.00 *p < 0.05 (2-tailed); ґ – mean; SD – standard deviation; Med – median; Min-Max – minimal-maximal value; T1 – Standardized lateral cephalometric radiographs obtained before preoperative orthodontic treatment; T2 – Standardized lateral cephalometric radiographs obtained 6 months after the surgical treatment. See abbreviations in Addendum.

Miković ND, et al. Vojnosanit Pregl 2016; 73(4): 318–325. Page 322 VOJNOSANITETSKI PREGLED Vol. 73, No. 4 Table 3 Changes in distances between the reference points and X axis Distances (mm) n ґ SD Med Min Max p T1 21 71.86 13.28 71.00 45.00 95.00 0.644 XB T2 21 73.29 9.03 71.00 61.00 96.00 XA T1 21 35.38 13.20 32.00 23.00 88.00 0.137 T2 21 32.19 5.78 30.00 24.00 49.00 XDI T1 21 5.24 2.91 5.00 0.00 11.00 0.040* T2 21 6.86 3.41 7.00 0.00 14.00 XPI T1 21 3.62 1.99 4.00 0.00 8.00 0.887 T2 21 3.81 3.17 3.00 0.00 12.00 XCd T1 21 4.33 3.79 4.00 0.00 16.00 0.263 T2 21 3.57 2.73 3.00 0.00 8.00 XDC T1 21 8.48 5.47 11.00 0.00 16.00 0.335 T2 21 9.10 6.20 10.00 0.00 17.00 XAr T1 21 12.86 4.05 12.00 6.00 20.00 0.007* T2 21 14.57 4.25 14.00 8.00 21.00 XGo T1 21 58.05 10.67 57.00 40.00 82.00 0.058 T2 21 61.90 5.20 62.00 51.00 75.00 *p < 0,05 (2-tailed); ); ґ – mean; SD – standard deviation; Med – median; Min-Max – minimal-maximal value; T1 – Standardized lateral cephalometric radiographs obtained before preoperative orthodontic treatment; T2 – Standardized lateral cephalometric radiographs obtained 6 months after the surgical treatment. See abbrevations in Addendum.

showed the trend to move upward (0.19 mm and 0.62 mm, A positive correlation between the distance YB and respectively). On the contrary, point Cd showed the tendency to the angle SNB, YA and SNB was noted. The distance move downward (0.76 mm; p = 0.263) (Table 3). between the Y axis and the point DI showed a positive cor- The results suggest that point Ar was moved significantly relation with the angle ArGoMe (Table 6). from both X and Y axis. Point Ar moved downward (mean dif- ference T2-T1 was 1.71 mm; p = 0.007) and forward (T2-T1 Discussion was 1.53 mm; p = 0.005) (Tables 2 and 3). SNA, SNB and ANB angle significantly changed Condyle displacement from or in the glenoid fossa can postoperatively. SNA and ANB angle increased in dimensions be caused by abnormal mandibular movement, methods used (T2-T1) for 1.76° and 3.76° respectively (p = 0.049 and p < for fixation, segment rigidity, or masticatory muscle tensi- 0.001). On the other hand, SNB angle decreased for 1.95° (p = on 17. Condylar displacement, especially after BSSO, can ca- 0.04). Angles which predicted the rotation of the condyle – Ar- use postoperative complications 18. Rotational changes also GoMe changed significantly (p = 0.009) for 5.1°, but Cd-DC- contribute to idiopathic condylar resorption after BSSO 14–16. Xi/FH did not (p = 0.277). The rotation of maxilla (SnaSnp/FH The direction of movement of the jaw during surgery is of angle) did not change significantly six months after the surgery great importance because it is considered to be one of the (p = 0.128) (Table 4). factors that influence the postoperative position of the The study showed a positive correlation between the condyle 3. This study shows a statistically significant move- distance XB and the ArGoMe angle. The XA distance also ment of the mandible six months after the surgery, which correlated negatively with ArGoMe angle. The distance significantly influenced the position of the condyle. Studies between the point DI and the X axis showed negative corre- have shown that the method of fixation of fragments contri- lation with SNA angle (Table 5). butes significantly to the stability of the condyle 8, 16, 19, for

Table 4 Changes in angular parametres Angle (°) n ґ SD Med Min Max p T1 21 81.86 5.51 82.00 72.00 96.00 0.049* SNA T2 21 83.62 5.59 84.00 74.00 94.00 SNB T1 21 86.57 6.03 88.00 77.00 103.00 0.040* T2 21 84.62 5.04 84.00 75.00 92.00 ANB T1 21 -4.71 2.41 -4.00 -10.00 0.00 < 0.001** T2 21 -0.95 2.62 -1.0 -6.00 3.00 ArGoMe T1 21 139.48 7.94 137.00 126.00 155.00 0.009* T2 21 134.38 8.55 134.00 119.00 154.00 Cd-DC-Xi/FH T1 21 61.90 6.20 62.00 43.00 70.00 0.277 T2 21 63.76 6.36 63.00 52.00 77.00 SnaSnpFH T1 21 4.10 3.27 4.00 0.00 9.00 0.128 T2 21 5.19 3.37 5.00 1.00 11.00 *p < 0.05 (2-tailed); ** p < 0.001 (2-tailed); ); ґ – mean; SD – standard deviation; Med – median; Min-Max – minimal-maximal value; T1 – Standardized lateral cephalometric radiographs obtained before the preoperative orthodontic treatment; T2 – Standardized lateral cephalometric radiographs obtained 6 months after the surgical treatment. See abbrevations in Addendum.

Miković ND, et al. Vojnosanit Pregl 2016; 73(4): 318–325. Vol. 73, No. 4 VOJNOSANITETSKI PREGLED Page 323 Table 5 Correlation of angular and linear parametres (Xaxis) (T1-T2) Cd-DC-Xi / SnaSnp/FH ArGoMe SNA SNB ANB n = 21 FH r 0.009 -0.031 0.652** -0.206 -0.303 0.194 X B p 0.969 0.893 0.001 0.371 0.182 0.400 r 0.069 -0.188 -0.619** 0.041 0.280 -0.347 X A p 0.768 0.415 0.003 0.859 0.218 0.123 r -0.063 -0.053 0.148 -0.509* -0.360 -0.191 X DI p 0.787 0.818 0.523 0.018 0.109 0.406 r -0.067 -0.053 0.037 -0.130 -0.340 0.237 X PI p 0.775 0.818 0.873 0.574 0.131 0.300 r 0.193 0.374 0.232 -0.238 -0.394 0.177 X Cd p 0.403 0.095 0.311 0.299 0.077 0.442 r 0.077 0.010 -0.089 -0.414 -0.245 -0.261 X DC p 0.740 0.966 0.702 0.062 0.284 0.252 r -0.234 -0.123 0.261 -0.207 -0.146 -0.041 X Ar p 0.308 0.594 0.252 0.368 0.527 0.860 r 0.035 -0.171 -0.339 0.074 0.274 -0.252 X Go p 0.881 0.457 0.133 0.749 0.229 0.271 *Correlation is significant at the level p < 0.05 (2-tailed); **Correlation is significant at the level p < 0.01 (2-tailed); (T1-T2) – The difference in dimensions in angles/distances before the preoperative orthodontic treatment and six months after the correction of mandibular prognathism. See abbrevations in Addendum.

Table 6 Correlation of angular and linear parametres (Y axis) (T1-T2) Cd-DC-Xi / SnaSnp/FH ArGoMe SNA SNB ANB n = 21 FH r -0.303 -0.005 -0.027 0.379 0.680** -0.360 Y B p 0.181 0.983 0.906 0.090 0.001 0.109 Y A r -0.174 -0.053 -0.218 0.422 0.499* -0.112 p 0.450 0.819 0.343 0.057 0.021 0.630 Y DI r -0.099 0.078 0.498* -0.235 -0.061 -0.194 p 0.668 0.738 0.022 0.306 0.793 0.398 Y PI r 0.204 -0.393 -0.370 -0.308 -0.234 -0.090 p 0.374 0.078 0.099 0.175 0.308 0.700 Y Cd r -0.328 -0.123 0.178 -0.067 0.071 -0.163 p 0.147 0.595 0.440 0.774 0.759 0.481 Y DC r -0.294 -0.225 0.425 -0.179 -0.236 0.131 p 0.195 0.327 0.055 0.437 0.303 0.571 Y Ar r 0.112 0.206 0.422 -0.415 -0.276 -0.129 p 0.629 0.370 0.057 0.061 0.226 0.577 Y Go r 0.175 0.009 -0.275 0.193 0.189 0.081 p 0.447 0.969 0.227 0.401 0.413 0.727 *Correlation is significant at level p < 0.05 (2-tailed); **Correlation is significant at level p < 0.01 (2-tailed); (T1-T2) – difference in dimensions in angles/distances before preoperative orthodontic treatment and six months after the correction of mandibular prognathism. See abbrevations in Addendum.

these reasons, in this study the patients’ jaw fragments were ment of the condyle after BSSO and intraoral vertical ramus connected with rigid fixation. osteotomy, but there was no statistically significant difference Many researchers, using various radiographic methods, between these different techniques. The possible reason for mo- studied the movement of the condyle in patients after orthognat- ving the condyle forward and downward is anatomical feature of hic surgery 20–22. However, there are still few studies that deal the front part of the glenoid fossa 3. with bimaxillary orthognathic surgery mandibular prognat- On the other hand, Hu et al. 26 investigated the effect of sa- hism 23, 24. In this study, four points on the condyle – DI, PI, DC gittal split ramus osteotomy of the mandible on the temporo- and Cd were used and based on the distance of these points with mandibular joint. By comparing images of temporomandibular the X and Y axis the anteroposterior and vertical changes in po- joints, they noticed a posterior condyle movement in the group sition of the condyle before the preoperative orthodontic prepa- of patients who underwent BSSO. They also found the forward ration and 6 months after the bimaxillary surgical correction rotation of the condyle, which is similar to our results. These re- were established. The results of this study indicate the condyle sults can be explained by the pulling force of the anterior and tend to move forward and upward. The anterior condyle move- posterior segments of m. temporalis and m. masseter. In this ment is similar with the study which Ueki et al. 25 conducted. study there was a decrease in the value of the angle ArGoMe six They also reported that there was anterior and inferior move- months after the surgery which could partialy influence the

Miković ND, et al. Vojnosanit Pregl 2016; 73(4): 318–325. Page 324 VOJNOSANITETSKI PREGLED Vol. 73, No. 4 forward rotation of the condyle. Contrary to the results of Hu et Conclusion al. 26, a study by Harris et. al. 27 showed medial, posterior and superior movement of the condyle after BSSO, and also medial This study shows that the position of the condyle after rotation of the condyle. bimaxillary orthognathic surgery is altered. In our group of pati- The results showed that the amount of the mandibular ents, six months after surgery, the condyles tend to migrate and maxillar movement postoperatively did not correlate upward and forward. Only the most distal point on the head of statistically with condylar displacement as did the results of the condyle (point DI) correlated with the gonial and SNA an- Harris et al. 27 and Lee and Park 3. Interestingly, only changes gle. Although this study yielded significant results over a period in ArGoMe angle correlated with the changes in the distance of six months, it was performed in a limited number of patients Y-DI, and changes in the angle SNA correlated with changes due to strict inclusion criteria. Further research on changes in in the distance X-DI. condylar position is needed with a longer observation period. REFERENCES

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Addendum

Abbreviations:

S (sella) – The point representing the geometric center of the sella turcica; N (nasion) – The most anterior (midline) point of the frontonasal suture; A (subspinale) – The deepest point in the bony concavity in the midline below the anterior nasal spine; Or (orbitalis) – The point representing the lowest point on the inferior orbital rim; Po (porion) – The most superior point of the external auditory meatus; Sna (spina nasalis anterior) – The most prominent point of maxilla; Snp (spina nasalis posterior) – The most distal point of the conjunction of palatinal bone and pterygomaxillar fissure; B (supramentalis) – The innermost point on the contour of the mandible between the incisor tooth and the bony chin; Me (menton) – The lowest point of the mandibular symphysis; Go (gonion) – the midpoint of the mandibular angle between the ramus and mandibular body; Cd (condylion) – the most posterosuperior point on head of the condyle; Ar (articularis) – The point midway between the two posterior borders of the left and the right mandibular rami at the intersection with the basilar portion of the occipital bone; DI – The most distal point on the head of the condyle; PI – The most anterior point on the head of the condyle; DC – The center point of the collum mandibulae on the Ba-N line; Xi – The point located at the geographic center of the ramus; Ba (basion) – The point of the anterior margin of the foramen magnum – The midpoint of the curvature between upper and the lower surfaces of the basilar portion of the occipital bone. N-S – The main plane of the anterior cranial base; Go-Me – The main plane of the mandible body; Sna- Snp – The main plane of the maxilla; Cd-DC-Xi – the centerline of the mandibular rami; X axis (Or-Po Frankfort horizontal (FH)) – The horizontal plane of the head; Y axis – The vertical plane which is normal to the X osis and goes from the point S.

Miković ND, et al. Vojnosanit Pregl 2016; 73(4): 318–325.